Blind stitch sewing machine and blind stitching method

Abstract

A blind stitch sewing machine includes a straight needle, a driving mechanism which gives a linear reciprocating motion to the straight needle, a needle guide which prevents the straight needle from sliding on the surface of the work without sticking therein, and a work raising portion formed on a work raising member so that a raised part of the work is continuously raised until it is stuck with the pointed tip of the straight needle and, after the pointed tip of the straight needle has passed the work raising member, the work raising member is withdrawn from the path of the straight needle by a distance not less than the radius of the trunk of the straight needle. Also disclosed is a blind stitching method which comprises employing a straight needle, giving a linear reciprocating motion to the straight needle in a direction which is parallel to the plane in which the work spreads and which is orthogonal to the sewing direction, preventing the straight needle from sliding on the surface of the work without sticking therein, and actuating the work raising member such that, after the pointed tip of the straight needle has passed the work raising member, the work raising member is withdrawn from the path of the straight needle by a distance not less than the radius of the trunk of the straight needle.

What is claimed is: 
     
       1. A blind stitch sewing machine comprising: a needle plate having an aperture;   a press member and spring means for biasing said press member against a first surface of said needle plate to clamp a workpiece therebetween;   work feed means for feeding the workpiece in a first linear path along said first surface of said needle plate as the workpiece is blind-stitched;   a straight needle mounted on the opposite side of said needle plate relative to said first surface;   a needle guide which, in cooperation with said needle plate, defines a confined straight path for the motion of said needle, said needle guide pressing said needle downward against said needle plate;   needle drive means for driving said needle with linear reciprocating motion in a second linear path, said second linear path being parallel to said needle plate and orthogonal to said first linear path during stitching;   work engaging means for pushing a portion of the workpiece through said aperture into said second path to allow said needle to pierce said workpiece; and   a looper and looper drive means for driving said looper in synchronized cooperation with said motion of said needle to blind stitch the workpiece with a single-yarn chain stitch.   
     
     
       2. The blind stitch sewing machine of claim 1 wherein said first surface of said needle plate is its lowermost surface and said workpiece is pushed upwards through said aperture by said work engaging means. 
     
     
       3. The blind stitching machine of claim 1 further comprising a motor driven drive shaft and first means mounted on said drive shaft for driving said needle drive means and second means mounted on said shaft for driving said looper drive means. 
     
     
       4. The blind stitching machine of claim 3 wherein said first means is a cam and said needle drive means includes a rod driven with linear reciprocation by said cam and said second means is a crank and said looper drive means includes a joint member pivotally connected to said crank at a point offset from the axis of rotation of said drive shaft. 
     
     
       5. The blind stitch sewing machine of claim 1 further comprising work holding means for holding in position for stitching that portion of the workpiece delivered through said aperture by said work engaging means. 
     
     
       6. The blind stitch sewing machine of claim 5 wherein said work engaging means is a rotatable disk having an inverted V-shaped peripheral portion and said work holding means has a V-shaped groove which mates with said V-shaped peripheral portion of said work engaging means. 
     
     
       7. A blind stitch sewing machine comprising: a needle plate having an aperture;   a press member and spring means for biasing said press member against a first surface of said needle plate to clamp a workpiece therebetween;   work feed means for feeding the workpiece in a first linear path along said first surface of said needle plate as the workpiece is blind-stitched;   a straight needle having a trunk tapering to a point and mounted on the opposite side of said needle plate relative to said first surface;   needle drive means for driving said needle with linear reciprocating motion in a second linear path, said second linear path being parallel to said needle plate and orthogonal to said first linear path during stitching;   work engaging means for pushing a portion of the workpiece through said aperture into said second path to allow said needle to pierce said workpiece, said work engaging means comprising a rotatably driven disk mounted in a plane perpendicular to said needle plate and means for driving said disk with continuous rotation, said disk having a circumference spaced from the trunk of said needle and at least one protrusion extending radially from said circumference of said disk to a peak, said peak travelling in a circle as said disk rotates, said circle intersecting said second linear path, the peak of said protrusion extending outwardly of said circumference by a distance at least equal to the radius of said trunk of said needle; and   a looper and looper drive means for driving said looper in synchronized cooperation with said motion of said needle to blind stitch the workpiece with a single-yarn chain stitch.   
     
     
       8. The blind stitch sewing machine of claim 7 wherein said disk carries a plurality of said protrusions symmetrically positioned on said periphery. 
     
     
       9. The blind stitch sewing machine of claim 8 wherein said disk carries two of said protrusions and rotates a half turn per reciprocating motion of the needle. 
     
     
       10. The blind stitch sewing machine of claim 7 wherein each protrusion has at least one surface sloping away from said peak in a direction counter to the rotation of said disk to a juncture with said circumference, said sloping surface defining a radius for said disk which gradually diminishes from a maximum at said peak to a minimum at said juncture.